Method and system for assembling a rotor stack for an electric motor

ABSTRACT

The present disclosure is generally directed toward a method of assembling a plurality of rotor cores for an electric converter. The method includes placing, by a core robotic system employing force control feedback, a rotor core on a mandrel, and for each of the plurality of rotor cores, placing, a plurality of magnetizable inserts into a plurality of cavities in the rotor core by an insert assembly robotic (IAR) system employing force control feedback.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to copending applications filed concurrentlyherewith titled “ROTOR ASSEMBLY METHOD AND SYSTEM EMPLOYING CENTRALMULTI-TASKING ROBOTIC SYSTEM,” as filed in U.S. patent application Ser.No. 17/161,121 on Jan. 28, 2021, “METHOD AND APPARATUS FOR TRANSFERMOLDING OF ELECTRIC MOTOR CORES AND MAGNETIZABLE INSERTS,” as filed inU.S. patent application Ser. No. 17/161,175, on Jan. 28, 2021 and“INTEGRATED ROBOTIC END EFFECTORS HAVING END OF ARM TOOL GRIPPERS,” asfiled in U.S. patent application Ser. No. 17/160,762, on Jan. 28, 2021which are commonly assigned with the present application and thecontents of which are incorporated herein by reference in theirentireties.

FIELD

The present disclosure relates to assembly of a rotor and moreparticularly to, assembly of a rotor formed of multiple rotor cores.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Recent advancements in electric converters such as electric motorsand/or generators relate not only to performance, but also tomanufacturing, as the need for electric converters has increased invarious industries including automotive. More particularly, in theautomotive industry, electric motors can vary across different platformssince powertrain requirements of a small vehicle is different from thatof a truck. For example, with respect to the rotor of the electricmotor, the overall size of the rotor (e.g., diameter, height, etc.) tothe type of magnets installed, can vary platform-to-platform. Suchvariations can result in complex rigid assembly lines that impededynamic flexible configurations.

These and other issues related to the assembly of a rotor are addressedby the present disclosure.

SUMMARY

This section provides a general summary of the disclosure and is not acomprehensive disclosure of its full scope or all of its features.

The present disclosure is directed toward a method of assembling aplurality of rotor cores for an electric converter. The method includesplacing, by a core robotic system employing force control feedback, arotor core on a mandrel, and for each of the plurality of rotor cores,placing, a plurality of magnetizable inserts into a plurality ofcavities in the rotor core by an insert assembly robotic (IAR) systememploying force control feedback.

The following provides one or more variations of this method, which maybe implemented individually or in any combination:

In some variations, the IAR system includes a force control end-effectorconfigured to hold one or more magnetizable inserts, and placing theplurality of magnetizable inserts further includes acquiring, by theforce control end-effector, one or more magnetizable inserts from theplurality of magnetizable inserts, aligning the one or more magnetizableinserts with one or more cavities among the plurality of cavities, andreleasing, by the force control end-effector, the one or moremagnetizable inserts into the one or more cavities to have the one ormore magnetizable inserts independently descend into the one or more ofcavities.

In some variations, the IAR system includes a plurality of insertassembly robots to place the plurality of magnetizable inserts into theplurality of cavities and each of the plurality of insert assemblyrobots includes the force control end-effector.

In some variations, the method further includes rotating the mandrel toalign empty cavities of the rotor core with the IAR system to receivethe one or more magnetizable inserts from among the plurality ofmagnetizable inserts.

In some variations, the one or more magnetizable inserts are acquired ata first orientation of the end-effector and are aligned and released inthe one or more cavities at a second orientation different from that ofthe first orientation, and

In some variations, the method further includes changing orientation ofthe end-effector from the first orientation to the second orientationafter the magnetizable inserts are acquired.

In some variations, two or more magnetizable inserts are acquired andaligning the two or more magnetizable inserts further includes aligningand positioning, by the force control end-effector, a first magnetizableinsert of the two or more magnetizable inserts with a first cavity oftwo or more cavities among the plurality of cavities based on a forcefeedback detected a load cell of the force control end-effector, andaligning and positioning, by the force control end-effector, a secondmagnetizable insert of the two or more magnetizable inserts with asecond cavity of the two or more cavities in response to the firstmagnetizable insert being aligned with the first cavity.

In some variations, to align and position the second magnetizableinsert, the method further includes moving a portion of the forcecontrol end-effector having the second magnetizable insert a set offsetto align with the second cavity.

In some variations, placing the magnetizable inserts further includesgripping, at a first orientation, one or more magnetizable inserts fromthe plurality of magnetizable inserts by the IAR system, and aligningand positioning, at a second orientation different from the firstorientation, the one or more magnetizable inserts at one or morecavities among the plurality of cavities based on a force feedbackdetected by the IAR system.

In some variations, placing the magnetizable inserts further includesreleasing, by the IAR system, the one or more magnetizable inserts intothe one or more cavities, wherein the one or more magnetizableindependently descend into the one or more cavities.

In some variations, the plurality of magnetizable inserts includes afirst set of magnetizable inserts and a second set of magnetizableinserts, where the first set of magnetizable inserts is of a differentsize than that of the second set of magnetizable inserts.

In some variations, placing the magnetizable inserts further comprisessequentially placing N magnetizable inserts at a time into N cavitiesamong the plurality of cavities, where N is a number that is less than atotal number of magnetizable inserts to be placed.

In some variations, sequentially placing the magnetizable insertsfurther includes rotating the mandrel to align N empty cavities of therotor core with the IAR system to receive the N magnetizable inserts.

In some variations, placing the rotor core on the mandrel furtherincludes aligning, by the core robotic system, an alignment feature atan inner diameter of the rotor core with an alignment feature at anouter diameter of the mandrel based on a force feedback detected by thecore robotic system, and translationally moving, by the core roboticsystem, the rotor core along the mandrel based on the force feedbackdetected by the core robotic system.

In some variations, after the plurality of magnetizable inserts areplaced in a first rotor core from among the plurality of rotor cores,the method further includes aligning, by the core robotic system, asecond rotor core from among the plurality of rotor cores on the mandreland the first rotor core based on the force feedback.

In some variations, the method further includes controlling, by acontrol system, movement of the core robotic system and the IAR systemto have the core robotic system acquire the second rotor core prior tothe IAR system completing placement of the plurality of magnetizableinserts into the plurality of cavities.

In some variations, the method further includes transferring, by thecore robotic system, the plurality of rotor cores with the mandrel inresponse to completion of the assembly, and placing, by the core roboticsystem, a second mandrel for subsequent assembly of rotor cores.

In some variations, the method further includes monitoring force controlfeedback from the core robotic system, the IAR system or a combinationthereof; and determining an abnormal installation operation in responseto the monitored force control feedback exceeding a desired parameter.

In one form, the present disclosure is directed toward, a method ofassembling a plurality of rotor cores for an electric converter. Themethod includes placing, by a core robotic system employing forcecontrol feedback, a rotor core on a mandrel. For each of the pluralityof rotor cores, the method further includes acquiring, by an insertassembly robotic (IAR) system, N magnetizable inserts among a pluralityof magnetizable inserts at a time into N cavities among a plurality ofcavities employing force control feedback, where N is a number that isless than a total number of magnetizable inserts to be placed, aligning,by the IAR system, the N magnetizable inserts with the N cavities amongthe plurality of cavities by employing force control feedback, andreleasing by the IAR system, the N magnetizable inserts into the Ncavities to have the N magnetizable inserts independently descend intothe N cavities.

The following provides one or more variations of this method, which maybe implemented individually or in any combination:

In some variations, the IAR system includes at least one force controlend-effector configured to hold one or more magnetizable inserts.

In some variations, the method further includes controlling movement ofthe core robotic system and the IAR system to have the core roboticsystem acquire a subsequent rotor core from among the plurality of rotorcores prior to the IAR system completing placement of the plurality ofmagnetizable inserts into the plurality of cavities.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DRAWINGS

In order that the disclosure may be well understood, there will now bedescribed various forms thereof, given by way of example, referencebeing made to the accompanying drawings, in which:

FIG. 1 is a perspective view of a rotor in accordance with the presentdisclosure;

FIGS. 2A and 2B are exploded views of a mandrel having rotor core andmagnets in accordance with the present disclosure;

FIG. 3 illustrates a rotor assembly cell in accordance with the presentdisclosure;

FIGS. 4A, 4B, and 4C illustrate movement of an end-effector tool of aninsert assembly robot; and

FIG. 5 is a flowchart of an exemplary assembly routine of the rotorcores in accordance with the present disclosure.

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

In an exemplary application, a rotor for an electric converter, such asan electric motor or a generator, comprises a plurality of rotor coresfixedly secured to one another and a plurality of magnets disposedwithin the rotor cores, where the rotor cores and the plurality ofmagnets are fixedly secured to one another. The present disclosureprovides a method of assembling the rotor cores using force controlfeedback robotic systems that employ force control technology to monitorand adjust automated processes to, for example, position rotor cores ona mandrel and place magnetizable inserts into cavities defined withinthe rotor cores. In one form, the tolerance range associated with thesize of the cavity and the magnetizable inserts is typically tight(e.g., less than a millimeter) making it difficult to use othermonitoring techniques such as a vision system to control operation of arobotic system. The assembly method described herein can be employed fordifferent size rotor cores and/or magnetizable inserts and using thesame or substantially the same robotic systems. While the rotor assemblymethod is described in association with an electric motor, the samemethod can be employed with other suitable electric converters, such asa generator.

Referring to FIGS. 1, 2A, and 2B, a rotor assembly 100 of an electricmotor includes a plurality of rotor cores 102A to 102D (collectively“rotor cores 102”) and a plurality of magnetizable inserts 104 that aredisposed in the rotor cores 102. The rotor cores 102 are stackingly andcoaxially arranged with one another about a mandrel 106. Each rotor core102 defines a plurality of cavities 108 for receiving the plurality ofmagnetizable inserts 104. In one application, the plurality of cavities108 may be of different sizes to accommodate different size magnetizableinserts 104. For example, as illustrated, the plurality of cavities 108includes a first set of cavities 108A and a second set of cavities 108B,where the first set of cavities 108A are smaller in size than that ofthe second set of cavities 108B. In one form, the first set of cavities108A and the second set of cavities 108B are arranged in pairs to formfirst set pairs and second set pairs that are circumferentiallydistributed about the rotor core 102 and are arranged such that a pairof the first set of cavities 108A is disposed between a pair of thesecond set of cavities 108B and an outer perimeter 110 of the rotor core102.

The magnetizable inserts 104 include a material(s) having ferromagneticproperties such as, but not limited to, iron, neodymium, and nickel.Accordingly, the magnetizable inserts do not exhibit magnetic propertiesduring the rotor assembly, and only become magnets after undergoing amagnetizing process performed after the rotor is assembled. In one form,the plurality of magnetizable inserts 104 may be of different sizes. Forexample, as illustrated, the inserts 104 includes a first set ofmagnetizable inserts 104A to be disposed within the first set ofcavities 108A and a second set of magnetizable inserts 104B to bedisposed within the second set of cavities 108B, where the size of thefirst set of magnetizable inserts 104A is smaller than that of thesecond set of magnetizable inserts 104B. In one form, the first set ofmagnetizable inserts 104A form an outer magnetizable insert ring and thesecond set of magnetizable inserts 104B form an inner ring magnetizableinsert ring.

While the rotor cores 102 are provided as having different size cavities108 for different size magnetizable inserts 104, the rotor cores may beconfigured in other suitable ways. For example, the rotor core may onlyinclude one size of magnetizable inserts and thus, only have one sizecavities. In addition, the cavities do not have to be arranged in pairsas described and illustrated in the figures, and can be configured invarious suitable ways. In another example, the rotor core is configuredto have one or more magnetizable insert rings disposed circumferentiallyalong the rotor core. Accordingly, the present disclosure is applicableto other types of rotor cores having different cavities and/ormagnetizable inserts.

In one form, to assist in the assembly process, the rotor cores 102includes one or more alignment features at an inner diameter 120 tocorrespond with one or more alignment features provided at an outerdiameter 122 of the mandrel 106. For example, referring to FIG. 2B, therotor core 102C has, as an alignment feature, tabs 124 extendingradially inward at the inner diameter 120 of the rotor core 102C, andthe mandrel 106 has, as an alignment feature, slots 126 definedlongitudinally along the outer diameter 122 of the mandrel 106. The tabs124 of the rotor core 120 and the slots 126 are configured such that thetabs 124 extend into or mate with the slots 126 and the tabs 124 maytravel along the slot 126 during assembly. While specific example of thealignment features for the rotor core 102 and the mandrel 106 are shown,other suitable alignment features may also be used.

With reference to FIG. 3 , in one form, a rotor assembly cell 200 is amanufacturing cell to assemble and stack a plurality of rotor cores witha plurality of magnetizable inserts. The rotor assembly cell 200includes a core robotic system 202, an insert assembly robotic (IAR)system 204 having a first insert assembly (IA) robot 206A and a secondIA robot 206B (collectively “IA robot 206”), and a central controller208. As described further herein, the core robotic system 202 isconfigured to assemble rotor cores 210A to 210D (collectively “rotorcores 210”) on to a mandrel 212 and the IAR system 204 is configured toplace the magnetizable inserts in cavities of the rotor cores 212. Inone form, the central controller 208 is configured to control theoperation of the core robotic system 202 and the IAR system 204 tocoordinate movement therebetween and thus, assembly of the rotor cores210. In the following, the core robotic system 202 and the IAR system204 may collectively be referred to as robotic systems 202 and 204. Inone form, the rotor cores 210 and the mandrel 212 are provided as therotor cores 102 and the mandrel 106, respectively, and thus, the rotorcores 210 are assembled with magnetizable inserts that are similar tomagnetizable inserts 104.

The core robotic system 202 is a multi-axial industrial robotic arm 214with an end-of-arm tool 216 having a rotor core end effector 218 with anintegrated load cell 220 to provide force feedback. Specifically, theload cell 220 is configured to detect a force and torque having multipledegree of freedom (e.g., 6-degrees freedom) and output the detectedforce and torque as an electrical signal, which can then be analyzed.The load cell 220 may be strain gauge and/or other suitable forcedetecting device and is configured to detect along multiple axis.

In one form, the rotor core end effector 218 includes two opposingelongated members 222 having a dual V shaped portion or any number ofgeometries configured to interface with the outer perimeter of the rotorcore 210. Specifically, the end-of-arm tool 216 is configured to pick-upthe rotor core 210 from a core staging area 224 and align and assemblethe rotor core 210 on the mandrel 212. While a specific rotor coreend-effector 218 is illustrated, the rotor core end effector 218 havingthe integrated load cell 220 may be configured in other suitable ways.

The core robotic system 202 further includes a controller 226 (i.e., acore controller 226) for controlling movement of the robotic arm 214. Inone form, the core controller 226 is configured to employ force controlbased positioning in which the core robotic system 202 automaticallyadjusts movement of the robotic arm 214 having end-of-arm tool 216 froma programmed path based on force feedback detected by the load cell 220.For example, if the force feedback is greater than a defined value orprofile for the particular operation being performed, which may also beprovided as a desired parameter, the core controller 226 adjusts theposition of the end-of-arm tool 216 until the force feedback coincideswith the defined value/profile. Alternatively, if the force feedbackdoes not coincide with the desired parameter, the core controller 226determines the occurrence of an abnormal installation operation andnotifies the central controller 208.

In one form, the IAR system 204 includes two IA robots, where the firstIA robot 206A is configured to place a first set of magnetizable insertsinto a first set of cavities of the rotor core 210 and the second IArobot 206B is configured to place a second set of magnetizable insertsinto a second set of cavities. In one form, the IA robots 206 aremulti-axial (e.g., six axis) industrial robotic arms 228A and 228B withend-of-arm tools 230A and 230B having gripper end-effectors 232A and232B with integrated load cells 234A and 234B to provide force feedbacksimilar to the load cell 220. In the following the industrial roboticarms 228A and 228B are collectively referred to as “industrial roboticarms 228,” the end-of-arm tools 230A and 230B are collectively referredto as “end-of-arm tools 230,” the gripper end-effectors 232A and 232Bare collectively referred to as “gripper end-effectors 232,” and loadcells 234A and 234B are collectively referred to as “load cells 234.”The end-of-arm tools 230 may also be referred to as force controlend-effector(s).

In one form, each of the gripper end-effectors 232 is provided as atwo-finger grippers configured to retrieve and grip a magnetizableinsert. In one form, the end-of-arm tools 230 are further configured toacquire the magnetizable inserts at a first orientation and to align andrelease the inserts in respective cavities at a second orientationdifferent from that of the first orientation. For example, withreference to FIG. 4A to 4C, the end-of-arm tool 230 is configured toretrieve magnetizable inserts 231A and 231B at a first orientationprovided along an X-Y plane (FIG. 4A) and then change orientation toalign the inserts 231A and 231B above a core 233 along the Y-Z plane. Inaddition, in one form, at least one of the finger grippers of thegripper end-effector 232 is pivotable about an insert installation axis(e.g., axis Z) to position the inserts 231A and 231B in the cavities(not shown) that are skewed or slanted from one another (e.g., cavitiesin FIGS. 2A and 2B). An example of such an end-of-arm tool for the IArobot is disclosed in Applicant's co-pending application titled“INTEGRATED ROBOTIC END EFFECTORS HAVING END OF ARM TOOL GRIPPERS” whichis commonly owned with the present application and the contents of whichare incorporated herein by reference in its entirety. While the gripperend-effectors 232 are illustrated as having a pair of two-fingergrippers, the gripper end-effector 232 may include one or moretwo-finger grippers to retrieve one or more magnetizable inserts.

The IAR system 204 further includes one or more controllers 238 (i.e.,IAR controllers 238A and 238B in FIG. 3 ) for controlling movement ofthe robotic arms 228. In one form, similar to the core controller 226,the IAR controllers 238 are configured to employ force control basedpositioning in which the IA robots 206 automatically adjusts from aprogrammed path based on force feedback detected by the load cells 234.For example, if the force feedback is greater than a defined value orprofile (i.e., desired parameter) for the particular operation beingperformed such as, aligning and positioning magnetizable inserts withrespective cavities, the IAR controllers 238 adjust the position of theend-of-arm tools 230 until the force feedback resistance coincides withthe defined valued/profile. Alternatively, similar to the corecontroller 226, if the force feedback does not coincide with the desiredparameter, the IAR controllers 238 determines the occurrence of anabnormal installation operation and notifies the central controller 208.

While the IAR system 204 includes two IA robots 206, the IAR system 204may include one or more IA robots 206 based on, for example, theconfiguration of the rotor cores, the manufacturing parameters (e.g.,cycle time, part assembly quota, etc.), among other considerations. Inaddition, an IA robot may be configured to install different sizemagnetizable inserts, and thus, the IAR system 204 is not required tohave different IA robot for different sized magnetizable inserts.

By employing force control feedback, the robotic systems 202 and 204 areable to learn and adapt to the assembly process allowing flexibility.Accordingly, the core robotic system 202 is able to adapt to theassembly process allowing flexibility with respect to, for example,placement and positioning of rotor cores 210 irrespective of the size ofthe rotor core. In addition, the IAR system 204 can adapt tomanufacturing tolerances associated with the cavities of the rotor cores210.

In one form, the central controller 208 is configured to synchronouslycontrol the robotic systems 202 and 204 to assemble the rotor cores 210and is communicably coupled to the robotic systems 202 and 204 and morespecifically, the core controller 226 and the IARs controller 238, asillustrated by dash lines 225, 227 and 229 in FIG. 3 . The centralcontroller 208 may include a controller and/or a programmed logicalcontroller (PLC) to execute computer readable instructions forperforming the operations described herein and a user interface (notshown), such as a touchscreen display, a speaker, a microphone, amongothers. In particular, in one form, the central controller 208 isconfigured to centrally control the motion of the robotic system 202 and204 to improve overall assembly process efficiency and achievemanufacturing metrics such as cycle time and jobs per hour.

In one form, the central controller 208 is configured to monitoroperations of the robotic systems 202 and 204, and/or coordinatemovement of the robotic systems 202 and 204, among other functions suchas issue a notification if an abnormal operation has occurred. Moreparticularly, the robotic systems 202 and 204 may transmit data to thecentral controller 208 regarding whether a rotor core is positioned onthe mandrel, whether the IAR system 204 has placed magnetizable insertsinto cavities, and/or an occurrence of an abnormal operation, amongother information regarding the processes performed by respectiverobotic systems 202 and 204. Based on these determinations, the centralcontroller 208 is configured to instruct the robotic systems 202 and 204on performing subsequent steps such as having the IAR system 204 placenext set of magnetizable inserts, have the core robotic system 202position the next rotor core onto the mandrel, have the core roboticsystem 202 transfer the assembled rotor cores, and/or stop the rotorassembly and issue a notification to the user regarding the abnormaloperation.

Furthermore, in one form, the central controller 208 is configured toobtain data regarding the force control feedback performed by therobotic systems 202 and 204 and analyze the data to determine trendsassociated with the rotor assembly process. For example, the centralcontroller 208 is configured to associate the force feedback withabnormal operations to track number of occurrences which can then beused to detect quality issues in the rotor cores and/or the magnetizableinserts. In another example, the central controller 208 is furtherconfigured to include machine learning logic to improve automation ofthe tasks by recognizing patterns in force feedback and positionaladjustments made to perform an installation.

In one form, the central controller 208, the core controller 226, andthe IARs controller 238 form a control system for controlling theoperations the described herein. In one variation, the centralcontroller 208 may be omitted and thus, the control system includes thecore controller 226 and the IARs controller 238 for performing theoperations described herein. For example, the core controller 226 andthe IARs controllers 238 are communicably coupled to one another viawired and/or wireless communication links to coordinate operations andtransmit notifications. In addition, the core controller 226 and/or theIARs controllers 238 are configured to detect abnormal operations of therobotic system 202 and 204, determine trends associated with the rotorassembly process, and/or employ learning logic to improve automation ofthe tasks, as described above with the central controller 208.

In one form, the rotor assembly cell 200 also include a worktable 240and magnetizable insert cartridge feeders 242A and 242B (collectively“insert cartridge feeders 242”). The worktable 240 supports the rotorcore(s) 210 and the mandrel 212 and, in one form, is rotatable. Moreparticularly, in one form, the worktable 240 is operable by the centralcontroller 208, as represented by dashed line 241 in FIG. 3 , toautomatically rotate an incremental amount to align the IAR system 204with cavities of the rotor core 210. If the central controller 208 isnot employed, the worktable 240 may be operable by the core controller226 and/or the IARs controllers 238. It should be readily understoodthat rotatable worktable 240 is not required for aligning the cavitieswith the IAR system 204. For example, the IAR system 204 may employmultiple IA robots 206 that are configured to sequential place theinserts in the cavities.

The insert cartridge feeders 242 are configured to hold and dispense themagnetizable inserts to be assembled in the rotor core, and one or morecartridge feeders 242 may be provided for each of the IA robots 206. Inthe example application, the insert cartridge feeders 242A for the firstIA robot 206A holds the first set of magnetizable inserts and the insertcartridge feeders 242B for the second IAR hold the second set ofmagnetizable inserts. In an example application, an insert cartridgefeeder 242 includes a cartridge 244 holding multiple magnetizableinserts from the plurality of magnetizable inserts and a pneumatic slide246 to dispense a single magnetizable insert at a time from thecartridge 244. In the example application, the cartridge 244 is arrangedas a vertical tower. While four cartridge feeders 242 are illustrated,one or more cartridge feeders 242 may be employed based on the number ofIA robots, the type of magnetizable inserts, among other considerations.In addition, while specific cartridge feeders are illustrated othersuitable dispensers may be used for automatically dispensing themagnetizable inserts.

Referring to FIG. 5 , an example assembly routine 400 performed with therotor assembly cell 200 is provided. At 402, the core robotic system 202places a first rotor 210A on the worktable with the mandrel 212. Thatis, in one form, the first rotor core 210 from among the plurality ofrotor cores is preassembled with the mandrel 212 and provided at thepallet area 224 with the other rotor cores 210B, 210C, 210D. As such, at402, the core robotic system 202 picks up and transfers the first rotorcore with the mandrel to the worktable 240 and in one form, transmits asignal indicating completion of placement to the central controller 208to trigger placement of magnetizable inserts.

At 404, the IAR system 204 places a plurality of magnetizable insertsinto a plurality of cavities in the rotor core (i.e., the first rotorcore). Specifically, the first IA robot 206A obtains and grips one ormore magnetizable inserts from the first set of magnetizable insertsprovided at the insert cartridge feeders 242A. The first IA robot 206Athen aligns and positions the magnetizable inserts from the first set ofmagnetizable inserts into one or more cavities from the first set ofcavities based on a force feedback detected by the load cell of thefirst IA robot 206. In one form, the one or more cavities from the firstset of cavities are directly adjacent to one another. In another form,one or more cavities are separated from another by at least one othercavity.

In one form, in aligning the magnetizable inserts, the first IA robot206A is configured to position and align a first magnetizable insertinto a first cavity, and once aligned, position and align the othermagnetizable insert(s) based on a set offset. Accordingly, themagnetizable inserts are staggeredly placed in the cavities. In oneform, in positioning the magnetizable inserts, the first IA robot 206Ais configured to release the one or more of magnetizable inserts fromthe first set of magnetizable inserts into the one or more of cavities,such that the one or more of magnetizable inserts from the first set ofmagnetizable inserts independently descend into the one or more ofcavities. That is, the magnetizable inserts fall into respectivecavities via gravity. In another application, the first IA robot 206Amay apply some force to the one or more of magnetizable inserts toposition them within the cavity.

The second IA robot 206B obtains and grips one or more magnetizableinserts from the second set of magnetizable inserts provided at theinsert cartridge feeders 242B, and performs in a similar manner as thatof the first IA robot 206A to align and position of the magnetizableinserts with one or more cavities from the second set of cavities. Thus,details regarding such operation is omitted for brevity.

At 404, the central controller 208 coordinates movement of the IA robots206A and 206B such that the magnetizable inserts from the first set ofmagnetizable inserts and the second set of magnetizable inserts arepositioned at about the same time. Once the magnetizable inserts areplaced, the IAR system 204 notifies the central controller 208 and thecentral controller 208 automatically rotates the mandrel 212 having therotor core 210A to align empty cavities of the rotor core 210A with theIAR system 204 to place the next set of magnetizable inserts intorespective cavities. For example, the central controller 208 rotates theworktable 240 supporting the mandrel 212 and the rotor core(s) 210 toalign the empty cavities. In one form, at 404, the central controller208 is configured to track the placement of the magnetizable insertsbased on, for example, the number of rotations, the number of completionnotifications from the IAR system 204, and/or the number of magnetizableinserts retrieved from the insert cartridge feeders 242, among othermethods.

At 406, after the plurality of magnetizable inserts are assembled in theplurality of cavities, the central controller 208 determines ifadditional rotor cores 210 are to be assembled. For example, the centralcontroller 208 may maintain a counter for determining the number ofrotor cores 210 assembled. If all the rotor cores 210 are assembled, thecentral controller 208 instructs the core robotic system 202 to transferthe stacked rotor cores. Specifically, the core robotic system 202, at408, transfers the rotor cores 210 with the mandrel 212 from theworktable 240 to a second area such as a mold-press operation.

If additional rotor cores 210 are to be assembled, the core roboticsystem 202, at 408, acquires the next rotor core 210 from the pallet 224and assembles it onto the mandrel 212. In one form, with the rotor core210 and mandrel 212 having alignment features as described above, thecore robotic system 202, using force feedback detected by the load cell,aligns the tabs of the rotor core 210 with the slots of the mandrel 212and then translationally moves the rotor core 210 along the mandrel 212until the rotor core 210 abuts against the preceding rotor core 210.Once the new rotor core 210 is positioned the routine proceeds toplacing the magnetizable inserts, at 404.

It should be readily understood that the routine 400 is for exemplarypurposes and that other routines may be provided. For example, in lieuof a first rotor core preassembled with the mandrel, the routine mayplace a mandrel stand onto the worktable and then place the first rotorcore onto the mandrel. In another example, a vision system may beprovided within the rotor assembly system to monitor macro motions suchas movement of rotor cores, retrieval of magnetizable inserts, transferof rotor core, among other processes.

Furthermore, the routine 400 may also vary based on the configuration ofthe rotor assembly cell and more particularly, the number of insertassembly robots of the IAR system. In one form, the rotor assembly cellmay sequentially place N magnetizable inserts at a time into N cavitiesamong the plurality of cavities, wherein N is a number that is less thana total number of magnetizable inserts to be placed. For example, in theapplication provided herein, N is 4 since there are two insert assemblyrobots. In another example, additional insert assembly robots may beprovided such that all the magnetizable inserts are placed into thecavities at once and/or without rotating the mandrel having the rotorcores.

Unless otherwise expressly indicated herein, all numerical valuesindicating mechanical/thermal properties, compositional percentages,dimensions and/or tolerances, or other characteristics are to beunderstood as modified by the word “about” or “approximately” indescribing the scope of the present disclosure. This modification isdesired for various reasons including industrial practice, material,manufacturing, and assembly tolerances, and testing capability.

As used herein, the phrase at least one of A, B, and C should beconstrued to mean a logical (A OR B OR C), using a non-exclusive logicalOR, and should not be construed to mean “at least one of A, at least oneof B, and at least one of C.”

The description of the disclosure is merely exemplary in nature and,thus, variations that do not depart from the substance of the disclosureare intended to be within the scope of the disclosure. Such variationsare not to be regarded as a departure from the spirit and scope of thedisclosure.

In this application, the term “controller” and/or “module” may refer to,be part of, or include: an Application Specific Integrated Circuit(ASIC); a digital, analog, or mixed analog/digital discrete circuit; adigital, analog, or mixed analog/digital integrated circuit; acombinational logic circuit; a field programmable gate array (FPGA); aprocessor circuit (shared, dedicated, or group) that executes code; amemory circuit (shared, dedicated, or group) that stores code executedby the processor circuit; other suitable hardware components thatprovide the described functionality, such as, but not limited to,movement drivers and systems, transceivers, routers, input/outputinterface hardware, among others; or a combination of some or all of theabove, such as in a system-on-chip.

The term memory is a subset of the term computer-readable medium. Theterm computer-readable medium, as used herein, does not encompasstransitory electrical or electromagnetic signals propagating through amedium (such as on a carrier wave); the term computer-readable mediummay therefore be considered tangible and non-transitory. Non-limitingexamples of a non-transitory, tangible computer-readable medium arenonvolatile memory circuits (such as a flash memory circuit, an erasableprogrammable read-only memory circuit, or a mask read-only circuit),volatile memory circuits (such as a static random access memory circuitor a dynamic random access memory circuit), magnetic storage media (suchas an analog or digital magnetic tape or a hard disk drive), and opticalstorage media (such as a CD, a DVD, or a Blu-ray Disc).

What is claimed is:
 1. A method of assembling a plurality of rotor coresfor an electric converter, the method comprising: providing a corerobotic system employing force control feedback and an insert assemblyrobotic (IAR) system; placing a rotor core of the plurality of rotorcores on a mandrel by the core robotic system employing force controlfeedback, wherein each one rotor core from the plurality of rotor coresincludes a plurality of cavities; and placing a plurality ofmagnetizable inserts into the plurality of cavities of the rotor core bythe insert assembly robotic (IAR) system employing force controlfeedback, wherein the IAR system includes a force control end-effectorconfigured to hold one or more magnetizable inserts from the pluralityof magnetizable inserts, wherein the placing the plurality ofmagnetizable inserts further comprises: acquiring, by the force controlend-effector, the one or more magnetizable inserts: aligning the one ormore magnetizable inserts with one or more cavities among the pluralityof cavities; and releasing, by the force control end-effector, the oneor more magnetizable inserts into the one or more cavities to have theone or more magnetizable inserts independently descend into the one ormore cavities.
 2. The method of claim 1, wherein the IAR system includesa plurality of insert assembly robots to place the plurality ofmagnetizable inserts into the plurality of cavities and each of theplurality of insert assembly robots includes the force controlend-effector.
 3. The method of claim 1 further comprising rotating themandrel to align empty cavities of the rotor core with the IAR system toreceive the one or more magnetizable inserts from among the plurality ofmagnetizable inserts.
 4. The method of claim 1, wherein: the one or moremagnetizable inserts are acquired at a first orientation of theend-effector and are aligned and released in the one or more cavities ata second orientation different from that of the first orientation, andthe method further comprises changing orientation of the end-effectorfrom the first orientation to the second orientation after themagnetizable inserts are acquired.
 5. The method of claim 1, wherein twoor more magnetizable inserts from the plurality of magnetizable insertsare acquired and aligning the two or more magnetizable inserts furthercomprises: aligning and positioning, by the force control end-effector,a first magnetizable insert of the two or more magnetizable inserts witha first cavity of two or more cavities among the plurality of cavitiesbased on a force feedback detected a load cell of the force controlend-effector; and aligning and positioning, by the force controlend-effector, a second magnetizable insert of the two or moremagnetizable inserts with a second cavity of the two or more cavities inresponse to the first magnetizable insert being aligned with the firstcavity.
 6. The method of claim 5, wherein to align and position thesecond magnetizable insert, the method further comprises moving aportion of the force control end-effector having the second magnetizableinsert a set offset to align with the second cavity.
 7. The method ofclaim 1, wherein the plurality of magnetizable inserts includes a firstset of magnetizable inserts and a second set of magnetizable inserts,wherein the first set of magnetizable inserts is of a different sizethan that of the second set of magnetizable inserts.
 8. The method ofclaim 1, wherein the placing the rotor core on the mandrel furthercomprises: aligning, by the core robotic system, an alignment feature atan inner diameter of the rotor core with an alignment feature at anouter diameter of the mandrel based on a force feedback detected by thecore robotic system; and translationally moving, by the core roboticsystem, the rotor core along the mandrel based on the force feedbackdetected by the core robotic system.
 9. The method of claim 1, whereinafter the plurality of magnetizable inserts are placed in a first rotorcore from among the plurality of rotor cores, the method furthercomprises aligning, by the core robotic system, a second rotor core fromamong the plurality of rotor cores on the mandrel and the first rotorcore based on the force feedback.
 10. The method of claim 9 furthercomprising controlling, by a control system, movement of the corerobotic system and the IAR system to have the core robotic systemacquire the second rotor core prior to the IAR system completingplacement of the plurality of magnetizable inserts into the plurality ofcavities.
 11. The method of claim 1 further comprising: transferring, bythe core robotic system, the plurality of rotor cores with the mandrelin response to completion of the assembly; and placing, by the corerobotic system, a second mandrel for subsequent assembly of rotor cores.12. The method of claim 1 further comprising: monitoring force controlfeedback from the core robotic system and the IAR system for determiningan abnormal assembling process based on operation in response to themonitored force control feedback exceeding a desired parameter.
 13. Amethod of assembling a plurality of rotor cores for an electricconverter, the method comprising: providing a core robotic systememploying force control feedback and an insert assembly robotic (IAR)system; placing a rotor core of the plurality of rotor cores on amandrel by the core robotic system employing force control feedback,wherein each one rotor core from the plurality of rotor cores includes aplurality of cavities; and placing a plurality of magnetizable insertsinto the plurality of cavities of the rotor core by the insert assemblyrobotic (IAR) system employing force control feedback, wherein theplacing the magnetizable inserts further comprises: gripping one or moremagnetizable inserts from the plurality of magnetizable inserts by theIAR system at a first orientation; and aligning and positioning, at asecond orientation different from the first orientation, the one or moremagnetizable inserts at the one or more cavities among the plurality ofcavities based on a force feedback detected by the IAR system.
 14. Themethod of claim 13, wherein the placing the magnetizable inserts furthercomprises releasing, by the IAR system, the one or more magnetizableinserts into the one or more cavities, wherein the one or moremagnetizable independently descend into the one or more cavities.
 15. Amethod of assembling a plurality of rotor cores for an electricconverter, the method comprising: providing a core robotic systememploying force control feedback and an insert assembly robotic (IAR)system; placing a rotor core of the plurality of rotor cores on amandrel by the core robotic system employing force control feedback,wherein each one rotor core from the plurality of rotor cores includes aplurality of cavities; and placing a plurality of magnetizable insertsinto the plurality of cavities of the rotor core by the insert assemblyrobotic (IAR) system employing force control feedback, wherein theplacing the magnetizable inserts further comprises sequentially placingN magnetizable inserts at a time into N cavities among the plurality ofcavities, wherein N is a number that is less than a total number ofmagnetizable inserts to be placed.
 16. The method of claim 15, whereinthe sequentially placing the magnetizable inserts further comprisesrotating the mandrel to align N empty cavities of the rotor core withthe IAR system to receive the N magnetizable inserts.